Antibacterial Effect of Low-Level Laser on Four-Week-Old Biofilm of Enterococcus Faecalis in Presence of Intracanal Medicaments: An in Vitro Study Publisher



Baghlouei SKY ; Fazyab M ; Esnaashari E ; Pourhajibagher M ; Kamali S
Source: Journal of Research in Dental and Maxillofacial Sciences Published:2026

Abstract

Background and Aim: This in vitro study assessed the impact of low-level laser irradiation (LLLI) on resistance of Enterococcus faecalis (E. faecalis) to calcium hydroxide (CH) and triple antibiotic paste (TAP) intracanal medicaments. Materials and Methods: In this in vitro study, 44 extracted single-rooted human teeth were categorized into 6 groups of negative control (n=2), positive control (n=2), TAP (n=10), CH (n=10), TAP+LLLI (n=10), and CH+LLLI (n=10). Following preparation, the samples were transferred to brain heart infusion (BHI) broth and incubated at 37°C for 24 hours; 1 mL of E. faecalis (ATCC 29212) suspension was injected into the canals and incubated for 4 weeks for biofilm formation. CH and TAP were introduced into the canals, depending on group allocation of the teeth, and LLLI with performed for 15 seconds using 980 nm diode laser with an energy density of 6.89 J/cm², power-output of 0.5 W, and a tip diameter of 10 mm. After 2 weeks, canal debris was removed using #4 Gates-Glidden drills and incubated in BHI at 37°C for 8 hours. Then, 100 μL of the dilution was cultured to determine the number of colony-forming units (CFUs), indicating the effectiveness of disinfection, after 12 hours. Data were analyzed with one-way ANOVA (alpha=0.05). Results: The four groups had no significant difference in colony count (P=0.483). Conclusion: The results of this study indicated that LLLI in combination with CH or TAP did not lead to a significant reduction in colony count compared to the use of CH or TAP alone. © 2026 Faculty of Dentistry, Tehran Medical Sciences, Islamic Azad University.